In recent years, organic LED display becomes more and more popular due to with self-luminous, fast response time and low power consumption features. However, the driving transistors, arranged in the driving circuit of the organic LED display, may have threshold voltage variations and thereby affecting the current for driving the organic LEDs or even leading the uneven brightness on the organic LEDs if the threshold voltage variations are serious.
In addition, with the development of the display technology, today's display consumes less power, has higher resolution and smaller size. However, the number of the scan signal lines of scan driver increases as well as the scan time of the scan driver decreases with increasing resolutions. Thus, it is important to those ordinarily skilled in the art to solve the threshold voltage variation problem and develop a pixel circuit capable of completing the compensation operations of the organic LED driving circuit in the limited scan time.